(CNN) -- A death-penalty trial of seven Baha'i prisoners accused of spying for Israel has been delayed, Iranian officials have told family members, according to the U.S. Baha'i Office of External Affairs.

The trial did not begin Saturday as scheduled and no date for its resumption has been given, the Baha'i office said. The government has not officially commented on the status of the trial.

The seven Baha'is have been held for more than a year without formal charges or access to their attorneys, said Diane Ala'i, representative to the United Nations for the Baha'i International Community.

She said the seven are being legally represented by Nobel Peace Prize laureate Shirin Ebadi and human rights lawyer Abdolfattah Soltani. But according to the human rights group Amnesty International, Soltani was arrested in Iran on June 16 and his whereabouts are unknown.

Ala'i said the lawyers have not had access to their clients, though they have been able to read their files.

The Iranian government has been under international pressure to release the Baha'i prisoners.

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Responding to a letter from Roxana Saberi, the Iranian-American journalist who spent four months in an Iranian jail earlier this year, the U.S. Commission on International Religious Freedom (USCIRF) has demanded the group be freed rather than stand trial on charges of espionage and religious violations. If convicted, they could face execution.

"In addition to the hundreds of Iranians who have been detained in the context of Iran's disputed presidential poll, many other 'security detainees' arrested long before the June election remain behind bars," Saberi said in her letter requesting U.S. government intervention in the Baha'i case.

"These Iranians and the authorities who have detained them need to know that the Iranian people's human rights are a matter of international concern," she said.

Saberi, who was tried, convicted and sentenced to eight years in prison on espionage charges, spent time in a cell at Tehran's Evin prison with two of the Baha'i prisoners. Saberi was released in May.

Leonard Leo, chairman of USCIRF, said last week that the crackdown on protests after Iran's June 12 presidential elections "have exposed the world to the cold realities about how the Iranian government regularly deals with dissent or views that are a perceived threat to the theocratic regime."

"The charges against these imprisoned Baha'is are baseless and a pretext for the persecution and harassment of a disfavored religious minority," Leo said. "They should be released immediately."

USCIRF, which is an independent bipartisan federal commission, said the seven Baha'is are charged under the jurisdiction of Branch 28 of Iran's Revolutionary Court, the same judicial process that convicted Saberi in April. The Baha'i prisoners are accused of spying for Israel, spreading propaganda against the Islamic Republic, and committing religious offenses.

"This trial is all about them being Baha'i," Ala'i said. "The accusations are completely false."

The Baha'i faith is a world religion that originated in 19th-century Persia, but Iran does not recognize it. Baha'is are regarded as apostates and heretics in Iran, where they have long been persecuted.

Ala'i said that, since the Islamic revolution in 1979, more than 200 Baha'is have been executed in Iran.

Iran denies that the Baha'i community is mistreated. Earlier this year, prosecutor general Qorban-Ali Dorri Najafabadi told state-run Press TV that the Iranian government has afforded the Baha'is "all the facilities offered to other Iranian citizens."

Najafabadi also said there is irrefutable evidence that many Baha'is are in close contact with Iran's enemies and have strong links to Israel.

The treatment of the Baha'is in Iran and the detention of the seven prisoners have attracted global attention.

Human Rights Watch, the world rights monitoring group, last month called for the release of the imprisoned or a prompt trial, with "fair and open proceedings."

Lawyer Cherie Blair, the wife of former British Prime Minister Tony Blair, wrote a newspaper column last week urging international pressure before the trial to "ensure the seven men and women receive a fair trial and a chance of justice."